Windshield wiper system with electric motor

ABSTRACT

In a windscreen wiper system with a wiper arm pivotally mounted and a drive causing the wiper arm to pivot. The drive has a reversible electrical motor and a control unit which switches the electrical motor. The motor has a housing in two sections. The first section can be mounted immovably in relation to the vehicle and includes the stator portion. The second section of the housing can turn in relation to the first, includes the rotor portion, and is connected to the wiper arm. The rotating second section of the housing is preferably provided with a bearing sleeve which is mounted on an axial supporting lug of the first section of the housing.

BACKGROUND OF THE INVENTION Field of the Invention

The invention relates to a windshield wiper system with a pivotablysupport wiper arm and a drive that swivels the wiper arm, the drivehaving a reversible electric motor mounted solidly to the vehicle and acontrol unit that switches the electric motor.

The windshield wiper systems are typically driven by an electric motorwhose direction of rotation is converted, via a gear and a crank into aback-and-forth motion of the wiper arm. Each crank drive is designed fora certain wiping angle, and adaptations to changing environmental andoperating conditions are hardly possible, or can be achieved only atmajor expense. Yet a windshield wiper system should be adapted to arelatively large number of different parameters, some of which cannot bemade even to agree with one another, which would include for instancethe wiper speed, the size of the field swept by the wipers, the parkingposition, the friction of the wiper blade on the wind shield,acceleration and deceleration values in the reversal region, and soforth. To avoid an overload from snow and the like, DE-A 41 04 565discloses a wiper system of the type referred to at the output, in whicha premature reversal of motion occurs if an overload is ascertained.

SUMMARY OF THE INVENTION

It is therefore the object of the invention to improve a windshieldwiper system further, and in order to better meet the existing demands,it proposes that the electric motor has a two-part housing, both partsof which are rotatable relative to one another, and that a first housingpart includes the stator portion of the electric motor and is mountablesolidly to the vehicle, and the second housing part includes the rotorportion and is connected to the wiper arm.

The use of a two-part housing for the reversible electric motor hasconstructional advantages above all, since the second housing partdriven by the motor can be associated directly with the wiper arm.Components such as crank drives, mounts and the like become unnecessary,saving space, and the assembly is simplified.

In a first embodiment, it is provided that connected to the secondhousing part is a bearing sleeve, which is supported on a supporting lugthat is disposed on the housing part that is solidly mounted to thevehicle. As a result, the drive mechanism and wiper arm support form asimple, easily mounted structural unit. In a preferred embodiment, thehousing part mountable solidly to the vehicle is embodied as cup-shaped,and the second housing part that is provided with the rotor portion isembodied as lidlike. In that case, the cup wall preferably has thestator portion of the electric motor.

The windshield wiper system becomes especially compact if the statorportion is provided on the supporting lug, and the second housing partis embodied as cup-shaped and forms an outer rotor portion, or if themotor power take-off shaft forms the bearing sleeve of the wiper arm. Inboth embodiments, the motor surrounds the supporting lug, which is fixedto the base body.

If the motor power take-off shaft is not the bearing sleeve of the wiperarm, then a further preferred embodiment provides that an intermediategear is embodied between the motor power take-off shaft and the bearingsleeve. With respect to the pivoting angle of the wiper arm, therotational angle of the electric motor becomes greater as a result inthe gear ratio of the intermediate gear, and can be adjusted moreexactly. This gear may be a spur gear, preferably a planetary gear.Moreover, the requisite drive moment of the electric motor decreases, sothat the motor can be made smaller. A space-saving accommodation can beattained if the cup wall of the housing part that is mountable solidlyto the vehicle, or the outer rotor portion, is provided with the ringgear of a planetary gear, and the second housing part has a supportingflange for the planet wheels.

A further embodiment provides that the supporting lug is disposedaxially adjustably on the housing part that is mountable solidly to thevehicle. This makes it possible to design windshield wiper systems inwhich the wiper arm can be deployed from an indented parking position,in which a parameter such as the contact force of the wiper blade can bevaried by means of the axial displacement, or in which by means of theaxial displacement a switchover between the wiper motion in the workingposition and swiveling into a parking position, for instance, can beattained.

The axial displacement can be done arbitrarily, for instance by means ofan electric motor, an electromagnet, a memory-effect spring, via apressure medium, etc, and this can also be controlled by the drivecontrol unit. The restoration to the initial position can be done viathe wiper drive mechanism or via a restoring spring.

For the aforementioned switchover of the pivoting between the workingposition and the parking position, a preferred embodiment provides thatan axially adjustable pawl is provided on the supporting lug, which pawlin a first position connects the supporting lug to the housing part thatis mountable solidly to the vehicle and in a second position connectsthe supporting lug to the bearing sleeve, in both cases in a mannerfixed against relative rotation. As a result, the electric motor of thewiper drive mechanism can move the wiper arm back and forth over therequired wiping angle and can move it into the parking position viaanother, arbitrarily selectable angle.

Preferably, the control circuit of the electric motor includes fuzzylogic, and optionally also includes a neural network. The windshieldwiper system can then be capable of adapting itself better and better toexisting parameters and to the operating conditions that arise.

In particular, by means of the invention, windshield wiper systems canbe achieved in which the wiper blade rotates relative to the wiper arm,while the wiper arm swivels over the windshield and in the processchanges its position, so that the wiper blade is guided at leastapproximately parallel, and the swept area of the windshield wiper isrectangular to trapezoidal, depending on the shape of the windshield. Inwindshield wiper systems of this kind, a harmonious wiper blade movementcan be attained if it is slowed down toward the reversal regions andaccelerated again after the reversal. For that purpose, the electricmotor is advantageously supplied with current pulses in very smallincrements, whose size is variable and which are defined by the controlunit. The embodiment of a planetary gear between the motor powertake-off shaft and the bearing sleeve brings additional advantages here,since the drive can be refined still further by the increased number ofangular increments.

The control unit can take the following fixed and variable magnitudes:the length and change in length of the wiper arm; angle and change inangle of the wiper blade relative to the wiper arm; contact force andchange in contact force of the wiper blade as a function of the vehiclespeed and the wiper blade speed; wiping angle and change in wipingangle; angle of pivoting to the parking position; angular speed andchange in angular speed of the wiper arm; forces of wiper systeminertia, and changes therein; friction and changes in friction betweenthe windshield and the wiper blade; wiping interval and changes in thewiping interval; etc. The invention will now be described in furtherdetail, in conjunction with the figures of the accompanying drawings,but without being limited thereto.

BRIEF DESCRIPTION OF THE DRAWING

FIGS. 1-8 are fragmentary axial sections through various exemplaryembodiments of the windshield wiper system according to the invention;FIG. 9 is a section taken along the line IX--IX of FIG. 10,corresponding to the exemplary embodiments of FIGS. 7 and 8; and FIG. 10is a section taken along the line X--X of FIG. 9.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

A windshield wiper system has a wiper arm 20 with a wiper blade, and thewiper arm has a bearing part 28 provided with a bearing sleeve 21. Thebearing sleeve 21 is disposed on a supporting lug 3 that protrudesupright centrally from a first housing part 1. The first housing part 1is provided with assembly straps 2, by means of which it is mountableinside the vehicle body 10 in a manner solidly connected to the vehicle.An electric motor 11, which in particular is a direct current motor, hasa hollow shaft as its power take-off shaft 14, which is coaxial with thesupporting lug 3 so that the electric motor surrounds the supporting lug3. A rotational angle detector 40 is associated with the electric motor11, and by way of it the magnitude of the rotational angle and therespective reversal points are determined. The bearing part 28 forms agear housing for a control gear of the wiper arm 20. The control gearconverts a relative rotation between the bearing part 28 of the wiperarm 20 and a part joined to the supporting lug 3 and protruding into thegear housing into a change in length of the wiper arm 20 and a rotationof the wiper blade, so that the wiper blade sweeps essentially theentire area of a windshield. The embodiment of the wiper arm 20 is notessential to comprehension of the present invention, however, and so itneed not be described in further detail. The bearing sleeve 21 cantherefore be provided on any other embodiment of a swivelable wiper armas well.

In the embodiment of FIG. 1, the first housing part 1 is cup-shaped, andthe cup wall 4 carries the stator portion 12 of the electric motor 11.Brushes 18 are provided in the region of the bottom. The rotor portion13 of the electric motor 11, in this embodiment, is fixed to the bearingsleeve 21, which therefore at the same time acts as the power take-offshaft 14. The bearing sleeve 21 carries a flange, which as the secondhousing part 22 forms a lid, provided with a sealing flange 16, of thefirst, cup-shaped housing part 1 and is rotatable relative to the firsthousing part 1. The second housing part 22 is therefore rotated by themotor and therefore simultaneously forms the bottom of the bearing part28 that is connected to the wiper arm 20. The rotational angle detector40 is located on the outside of the first housing part 1, between thecup wall 4 and the second housing part 22 that forms the lid.

In the embodiment of FIG. 2, a planetary gear 23 is embodied between thepower take-off shaft 14 of the motor and the bearing sleeve 21. Thebearing sleeve 21 is disposed coaxially inside the power take-off shaft14 and is provided with the second housing part 22, which forms thebottom of the bearing part 28 and the lid of the first housing part 1and in which axles 25 are disposed that carry planet wheels 24. Thepower take-off shaft 14 forms the sun wheel of the planetary gear, andthe cup wall 4 is provided with the internal gear wheel or ring gear 26.A gear ratio of 1:4 to 1:5, for instance, makes it possible to multiplythe rotational angle of the electric motor 11 by a factor of 4 or 5relative to the wiping angle, so that the control of the electric motorcan be refined. The electric motor 11 can moreover be switchedelectronically and includes not brushes but rather Hall sensors 17. Therotational angle detector 40 is disposed in the interior of the firsthousing part 1 and includes a perforated element 41, rotating with it,and a light source 42 and a light sensor 43. The remaining layout isequivalent to that of the embodiment of FIG. 1.

FIG. 3 shows an embodiment that as in FIG. 1 is embodied without aplanetary gear. The difference is that the second housing part 22,forming the bearing part 28, is cup-shaped and has both a bottom, on themiddle of which the bearing sleeve 21 is provided, and an outer wall 15.The outer wall 15 carries the rotor portion 13 of the electric motor 11,whose stator portion 12 is retained in a manner fixed against relativerotation on the supporting lug 3. The first housing part 1 takes theform of a plate, which embodies the sealingly inserted lid, which ismountable solidly to the vehicle, of the cup-shaped second housing part22. In this embodiment as well, it is possible to incorporate aplanetary gear 23.

In FIG. 4, an embodiment is shown in which the supporting lug 3 isaxially adjustable, and so the wiper arm 20 can be raised, for instancefrom an indentation in the vehicle body 10. The first housing part 1,which is again cup-shaped as in FIGS. 1 and 2, has a central sleeve 5,in which the supporting lug 3 is supported. Its actuation is effected bymeans of an actuating drive 30, which in this embodiment is formed by aheatable spring 34 with shape memory capability and by a counterpartspring 35. The spring 34 may be used either for the stroke or for thereturn. The actuating drive 30 may be embodied in any arbitrary way,however, and may for instance include an electric motor, a liftingmagnet, a pressure-fluid actuation means, etc. The remaining layout ofthis embodiment is essentially equivalent to that of the embodiment ofFIG. 2; the sealing flange 16, the internal gear wheel 26 and thetoothing of the sun wheel 29 on the power take-off shaft 14 have agreater height than the stroke or the displacement travel, asapplicable.

FIGS. 5-8 show embodiments of the windshield wiper system that have anadjustable-length wiper arm 20, which in its shortest length can betransferred to a parking position located outside the field swept by thewindshield wiper.

In the embodiment of FIG. 5, which again shows the raised position, thesupporting lug 3 is again supported displaceably in the central sleeve 5of the cup-shaped first housing part 1; the actuating drive 30 shownhere includes an electromagnetic lifting device 36, which is disposed onthe cup-shaped wall 4 of the first housing part 1 coaxially with thestator portion 12 and acts upon the rotor portion 13 of the electricmotor 11, which is axially displaceably connected to the supporting lug3. A restoring spring 39 acts counter to the lifting device 36. Thetoothing of the sun wheel 29 on the power take-off shaft 14 does notrequire an increased height, because after all the power take-off shaft14 is displaced jointly with the bearing sleeve 21 and the planet wheels24; instead, a free space 19 is made available underneath the rotorportion 13. For transferring the wiper arm 20 to the parking position, asecond actuating drive 47 is provided. It includes a cantilever arm 6,which is joined to the supporting lug 3 in a manner fixed againstrelative rotation but is not displaceable with it, and which is extendedto the outside through a slit in the first housing part 1. Thecantilever arm 6 has a sleeve 44, extending parallel outside the cupwall 4, in which a lifting magnet 32 and a locking pin 31 are disposed.A continuous 45 of the first housing part 1 has a bore that in thewiping position of the wiper arm 20 is aligned with the locking pin 31,and which is engaged by the locking pin 31 in the wiping position andfixes the supporting lug 3 solidly to the base body and hence solidly tothe vehicle. For the transfer to the parking position, the locking pinis released from the continuation 45 by means of the lifting magnet 32and introduced into a bore 37 of the sealing flange 16. This is done ina position of the wiper arm 20 in which the wiper arm has its shortestlength, which is not changed in the ensuing pivoting into the parkingposition. The pivoting initiated by the electric motor 11 thus rotatesthe supporting lug 3 jointly with the bearing sleeve 21 and the secondhousing part 22, via the planetary gear 23, the locking pin 31 and thecantilever arm 6, so that the control gear contained in the bearing part28 remains inoperative.

FIG. 6 shows a similar variant, in which the actuating drive 30 for thedisplacement of the supporting lug 3 again has a spring 34 with thecapability of shape memory. An arm 48 is radially secured to the lowerend of the displaceable supporting lug 3; this arm engages a groove 49,which rises helically over approximately 90°, in the recess 50 of thefirst housing part 1. The stroke of the spring 34 causes a rotation ofthe supporting lug 3, which in this embodiment, with the motor stop,would cause a change in length of the wiper arm 20. Since the stroke ofthe supporting lug 3 takes place only upon transfer of the wiper arm 20from the parking position to the working position, during which thewiper arm length must remain the same, the stroke height is ascertainedby a sensor 51, which rests on the flange or lid of the housing part 22and is acted upon by a spring 52. The axial joint displacement of thesensor 51 is detected by measurement coils 53 and transmitted to theelectric motor control unit, which in particular includes fuzzy logic.From the stroke of the sensor 51, the fuzzy logic calculates therotational angle of the supporting lug 3 and triggers the electric motor11, so that the bearing sleeve 21, the second housing part 22, thebearing part 28 and hence the wiper arm 20, via the planetary gear 23,are rotated synchronously with the supporting lug 3, until the terminalposition of the arm 48 is reached. In both terminal positions, thegroove 49 extends slightly axially, the result of which is the locking,in a manner fixed against relative rotation, of the supporting lug 3 tothe first housing part 1, as is required for the change in length of thewiper arm 20 during the wiping motion.

Two further embodiments, which have an actuating drive 47 for theswitchover of the wiper drive mechanism between the working position andthe parking position, are shown in FIGS. 7-10. In the embodiment of FIG.7, the stator portion 12 of the electric motor 11, which has twowindings 56, 57, is fixed to an annular wall 55 protruding upright fromthe first housing part 1. The rotor portion 13 is carried by the outerwall 15, which rotates jointly with the second housing part 22. Insidethe annular wall 55, space remains for the rotational angle measurementby means of a stationary light source 42, a light sensor 43, and aperforated element 41 that rotates jointly with the flange or lid of thehousing part 22, and also for the control unit 60, which in particularincludes fuzzy logic. The two windings 56 and 57 are designed anddisposed differently. By suitable triggering of the two windings, itbecomes possible to adapt the generatable torque to the forces required.For example, a torque that is higher by a factor of up to 8 is requiredat the reversal positions of the wiper arm. By suitable embodiment ofthe windings 56 and 57, and three or more windings may also be provided,a smaller winding can thus be provided in the middle region of the sweptfield of the windshield, the smaller winding being reinforced towardboth turning positions. In this embodiment, the assembly of the firsthousing part is effected by means of a central securing nut 59. To thatend, the first housing part 1 has a middle bottom screw 58, which ispassed through an opening of a part of the vehicle body 10 and fixed tothe other side of the nut 59. In this embodiment, the supporting lug 3is not supported axially displaceably, but only rotatably, in thecentral sleeve 5 of the first housing part 1. A locking pin 31 isaxially displaceable in the supporting lug 3, and an actuating drive 30is associated with this locking pin. The actuating drive 30, as in theembodiments of FIGS. 4 and 6, comprises a spring 34 with shape memorycapability and a restoring spring 3, which acts upon a pawl 33 that isextended to a slit 7 of the supporting lug 3. Details of the adjustmentwill be described below in conjunction with FIGS. 9 and 10.

In the embodiment of FIGS. 8-10, the supporting lug 3 is likewisesupported only rotatably in the central sleeve 5, and a locking pin 31is disposed axially displaceably in the supporting lug, and an actuatingdrive 30 is associated with the locking pin. The actuating drive 30includes a lifting magnet 32, which acts upon the portion of the lockingpin 31 that protrudes from the supporting lug 3, and a restoring spring35 acting on the locking pin 31 in the opposite direction. A pawl 33that passes through a diametrical slit 7 of the supporting lug 3 islikewise provided on the upper end of the locking pin 31. Both in theembodiment of FIG. 7 and in the embodiment of FIG. 8, the pawl 33 has aring 38 with teeth on its outside and inside, which is displaceable withthe locking pin 31. The internal toothing of the ring 38 slides into anexternal toothing 9 of the supporting lug 3. Widened portions areembodied in the upper end of the central sleeve 5 of the first housingpart 1 and in the lower end of the bearing sleeve 21, and each widenedportion carries one set of internal teeth 8 and 27. The supporting lug 3is as a result joined in a manner fixed against relative rotation eitherto the central sleeve 5, or in other words to the first housing part 1that is mountable solidly to the vehicle, or to the bearing sleeve 21 ofthe wiper arm 20, depending on the position of the ring 38. The pawl 33can also penetrate the control pin 31, so that it is guided incompulsory fashion in both directions. The remaining layout of thisembodiment is essentially equivalent to that of the embodiment of FIG. 1or FIG. 2. Instead of the lifting magnet 32, a spring with shape memorycapability can be used in this embodiment as well.

Various characteristics of the individual embodiments can also beemployed in other embodiments.

For instance, each embodiment with an axial motion can have instead of alifting magnet 32 a spring 34 with shape memory, an electric motor, anadjustment by means of a pressure medium, and so forth, and theadjusting drive and the restoring spring can also be transposed. The twoor more than two windings 56, 57 described in conjunction with FIG. 7can also be provided in the other embodiment. The planetary gear 23 mayalso be incorporated into all the embodiments. In the event that thedirect blocking of the second housing part 22 with the wiper arm 20 isnot possible for reasons of space, then the connection between therotating second housing part 22 and the bearing part 28 of the wiper arm20 can also be done via a steering arm, which transmits the rotarymotion of the housing part 22 to the bearing part 28 supported on thevehicle body.

I claim:
 1. In an automobile which includes a windshield wiper systemfor wiping a windshield, said system comprising:a wiper arm pivotallysupported on an automobile and drive means for pivoting said wiper arm,said drive means including a reversible electric motor stationarilymounted on the automobile and a control unit controlling said electricmotor, said electric motor having a stator portion and a rotor portion;a housing formed of a first housing part and a second housing partclosing off said first housing part, said first housing part carryingsaid stator portion of said electric motor and being stationarilymounted on the automobile, said second housing part being drivinglyconnected to said rotor portion of said electric motor, being rotatablerelative to said first housing part, and being non-rotatingly connectedto said wiper arm.
 2. The windshield wiper system according to claim 1,further comprising a bearing sleeve connected to said second housingpart, and a supporting lug disposed on said first housing part andsupporting said bearing sleeve.
 3. The windshield wiper system accordingto claim 2, wherein said stator portion is provided on said supportinglug, and said second housing part is a cup-shaped housing part definingsaid rotor portion as an outer rotor portion.
 4. The windshield wipersystem according to claim 3, further comprising a planetary gear with aring gear and planet wheels, said second housing part having asupporting flange formed thereon for supporting said planet wheels. 5.The windshield wiper system according to claim 4, wherein said ring gearis mounted on one of the cup wall of said first housing part and saidrotor portion.
 6. The windshield wiper system according to claim 2,wherein said electric motor includes a motor power take-off shaft, andsaid take-off shaft is formed by said bearing sleeve.
 7. The windshieldwiper system according to claim 2, wherein said electric motor includesa motor power take-off shaft, and including an intermediate geardisposed between and meshing with said motor power take-off shaft andsaid bearing sleeve.
 8. The windshield wiper system according to claim7, further comprising a planetary gear with a ring gear and planetwheels, said second housing part having a supporting flange formedthereon for supporting said planet wheels.
 9. The windshield wipersystem according to claim 8, wherein said ring gear is mounted on one ofthe cup wall of said first housing part and said rotor portion.
 10. Thewindshield wiper system according to claim 2, wherein said supportinglug is disposed axially adjustably on said first housing part.
 11. Thewindshield wiper system according to claim 2, further comprising anaxially adjustable pawl disposed on said supporting lug, said pawldefining a first position in which said pawl non-rotatably connects saidsupporting lug to said first housing part and a second position in whichsaid pawl non-rotatably connects said supporting lug to said bearingsleeve.
 12. The windshield wiper system according to claim 1, whereinsaid first housing part is cup-shaped, and said second housing part isformed as a lid.
 13. The windshield wiper system according to claim 12,wherein said stator portion is provided on a wall of said cup-shapedfirst housing part.
 14. The windshield wiper system according to claim13, further comprising a planetary gear with a ring gear and planetwheels meshing with said ring gear, said second housing part having asupporting flange formed thereon for supporting said planet wheels. 15.The windshield wiper system according to claim 14, wherein said ringgear is mounted on one of the cup wall of said first housing part andsaid rotor portion.
 16. The windshield wiper system according to claim1, wherein said control unit of said electric motor includes fuzzylogic.
 17. The windshield wiper system according to claim 1, whereinsaid control unit of said electric motor includes a neural network.